Exporting SharePoint to Drupal experience

My company needs to export a 3000 page SharePoint site which contain 500 sub sites. Has anyone tried to export data from SharePoint to Excel spreadsheet or CSV files? We did export some pages to Excel spreadsheet and found that the body section did not contain HTML formatted text. All images and url links, and tags were stripped out. We need to have the HTML in the spreadsheet file to be able to import it into the new Drupal 8 site using Migrate Source CSV. Does anyone know how to extract this body data from SharePoint? We may have to manually copy and paste each SharePoint page into Drupal. Thank you for any tips you have.

Source: https://www.drupal.org/taxonomy/term/37/feed